Method of allogeneic hematopoietic stem cell transplantation without graft failure or graft vs. host disease

ABSTRACT

The present invention provides a method of transplanting hematopoietic system reconstituting cells from a donor into an allogeneic recipient comprising administering to the recipient, prior to the administration of the hematopoietic system reconstituting cells, an amount of mononuclear cells which are treated so as to render them incapable of proliferating and causing a lethal graft versus host disease effect, but which are effective in enhancing subsequent engraftment of the hematopoietic system reconstituting cells in the recipient; and administering to the recipient an effective amount of hematopoietic system reconstituting cells.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of transplanting hematopoietic system reconstituting cells between genetically unrelated individuals using a combination of treated mononuclear cells and bone marrow or peripheral blood hematopoietic system reconstituting cells.

2. Background Art

Allogeneic bone marrow transplantation is the preferred treatment for a variety of malignant and genetic diseases of the blood and blood-forming cells. The widespread application of this therapy is limited by the availability of suitable bone marrow donors who are genetically related to the patient and share the same transplantation antigens on the surface of their blood cells. Only 25% of patients have a sibling who is an antigenically matched potential donor. Bone marrow transplantation can be offered to those patients who lack an appropriate sibling donor by using bone marrow from antigenically matched, genetically unrelated donors (identified through a national registry), or by using bone marrow from a genetically related sibling or parent whose transplantation antigens differ by one to three of six human leukocyte antigens from those of the patient. However, using antigenically mismatched, genetically related parent or sibling or antigenically matched, genetically unrelated donors, the likelihood of fatal graft vs. host disease (GvHD) and/or graft rejection increases from 20% for matched sibling donors to 50% in the cases of matched, unrelated donors and unmatched donors from the patient's family. Further, in cases where an unrelated donor is not matched at one of the six major transplantation antigens, graft rejection and/or fatal GvHD) increases to 60%.

GvHD is a disease with significant morbidity. Patients who develop acute GvHD may develop blisters covering most of their skin surface, massive gastrointestinal bleeding or fulminant liver failure and jaundice. Patients who develop chronic GvHD may develop scleroderma that results in joint contractures and skin ulcers, hair loss and a generalized wasting syndrome. Patients with acute or chronic GvHD are immuno-suppressed and at risk for life-threatening opportunistic infections similar to those that develop among AIDS patients.

The removal of T cells from the bone marrow obtained from matched unrelated or unmatched sibling donors results in a decreased incidence of graft vs. host reactions, but an increased incidence of rejection of the allogeneic bone marrow graft by the patient. Thus, lymphocytes, and especially T cells, present in the allogeneic bone marrow graft are important to ensure engraftment in antigenically and genetically mis-matched recipients. T cells present in the allogeneic graft also have an important role in eliminating residual cancer cells in the recipient, a phenomenon termed "graft vs. leukemia effect." The "ideal" donor T cell in an allogeneic bone marrow or stem cell graft would have the ability to prevent graft rejection and mediate the graft vs. leukemia effect without producing GvHD. The potential to successfully transplant T cell-depleted, or stem cell-enriched bone marrow or stem cells from antigenically mis-matched donors to patients without graft rejection or GvHD would greatly extend the availability of bone marrow transplantation to those patients without an antigenically matched sibling donor.

In a dog model of allogeneic bone marrow transplantation, the addition of viable donor lymphocytes to the bone marrow graft resulted in an increased frequency of stable engraftment, from 9% using antigenically mis-matched bone marrow alone, to 88%, using a combination of bone marrow and donor lymphocytes. However, all the animals that received donor lymphocytes died of lethal GvHD (Storb et al. (1968) "Marrow grafts by combined marrow and leucocyte infusions in unrelated dogs selected by histocompatability typing" Transplantation 6:587-593).

An alternative to infusions of viable donor lymphocytes has been the use of irradiated donor lymphocytic infusions in the post-transplant period. The addition of donor lymphocytes that had been previously irradiated to a dose of 20 Gy (2,000 rads) to allogeneic bone marrow cells did not prevent fatal graft failure when the mixture was administered to lethally irradiated dogs antigenically mismatched for dog leukocyte antigens (DLA), (Deeg et al. (1979) "Abrogation of resistance to and enhancement of DLA-nonidentical unrelated marrow grafts in lethally irradiated dogs by thoracic duct lymphocytes", Blood 53:552-587).

In genetically unrelated rabbits, a series of five infusions of donor lymphocytes, irradiated to 15 Gy (1,500 rads) one to ten days following the infusion of allogeneic bone marrow cells and irradiated autologous bone marrow cells decreased the rate of graft rejection from 60% to 20%, but only 30% of the treated animals survived more than 100 days with donor derived hematopoietic cells and 40% of animals that received T cell depleted bone marrow followed by irradiated allogenic lymphocytes developed GvHD. (Gratwohl et al. (1987) "Engraftment of T-cell depleted rabbit bone marrow" Acta haematol. 77:208-214).

The addition of antigenically matched viable donor lymphocytes obtained from the bone marrow donor and given 1-5 days post-transplant to 43 patients undergoing allogeneic bone marrow transplantation for aplastic anemia resulted in a 14% incidence of graft failure compared to 22% in a similar group of 20 patients who received the bone marrow transplant without additional donor lymphocytes. However, the incidence of acute GvHD was 36% in the group treated with donor lymphocytes compared to a 20% incidence of acute GvHD in the group that received bone marrow cells alone. In both groups, 20% of patients ultimately died of GvHD, (Storb et al. (1982) "Marrow transplantation with or without donor buffy coat cells for 65 transfused aplastic anemia patients", Blood 59:236-246).

In a clinical report describing the use of irradiated human lymphocytes, 20 patients with hematological malignancies were treated with high-dose chemotherapy and total body irradiation followed by the infusion of T cell-depleted antigenically matched, genetically related allogeneic bone marrow cells. One, three, five, seven and fourteen days following bone marrow transplantation, the patients received infusions of donor lymphocytes, irradiated to 15 Gy (1,500 rads). The authors reported no cases of graft failure, but noted an overall incidence of GvHD of 85% and a 15% incidence of fatal GvHD, (Gratwohl et al. (1988) "Irradiated donor buffy coat following T cell-depleted bone marrow transplants", Bone marrow transplantation 3:577-582).

These reports suggest that infusions of irradiated donor lymphocytes are not toxic to recipients of bone marrow transplantation, but do not demonstrate clear efficacy in either preventing graft rejection or GvHD. The present invention overcomes the problems in the art by providing a method of transplanting hematopoietic system reconstituting cells from a donor to an antigenically matched or unmatched, genetically unrelated recipient or an antigenically unmatched, genetically related recipient with successful engraftment in the absence of GvHD.

SUMMARY OF THE INVENTION

The present invention provides a method of transplanting hematopoietic system reconstituting cells from a donor into an allogeneic recipient comprising administering to the recipient, prior to the administration of the hematopoietic system reconstituting cells, an amount of mononuclear cells which are treated so as to render them incapable of proliferating and causing a lethal GvHD effect, but which are effective in enhancing subsequent engraftment of the hematopoietic system reconstituting cells in the recipient; and administering to the recipient an effective amount of hematopoietic system reconstituting cells.

In a specific embodiment, the present invention provides a method of transplanting bone marrow cells into an allogeneic recipient comprising administering to the recipient, one to five days prior to administration of the bone marrow cells, between 0.05×10⁶ and 30×10⁶ cells/kg of body weight of T cells that have been exposed to between 500 and 1000 rads of irradiation; and administering to the recipient between 1.0×10⁸ and 4.0×10⁸ T cell-depleted bone marrow cells/kg of body weight.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention may be understood more readily by reference to the following detailed description of specific embodiments and the Examples included herein.

In one embodiment, the present invention provides a method of transplanting hematopoietic system reconstituting cells from a donor source into an allogeneic recipient comprising administering to the recipient, prior to the administration of the hematopoietic system reconstituting cells, an amount of mononuclear cells which are treated so as to render them incapable of proliferating and causing a lethal GvHD effect, but which are effective in enhancing subsequent engraftment of the hematopoietic system reconstituting cells in the recipient; and administering to the recipient an effective amount of hematopoietic system reconstituting cells.

As used herein, "hematopoietic system reconstituting cells" means a population of cells, preferably human, that possess the capability of dividing and producing progeny that include all of the formed cellular elements of the blood. As used herein, "donor source" means the animal, preferably human, that is the natural source from which the hematopoietic system reconstituting cells are originally removed. Also as used herein, a "recipient" is the animal, typically human, into which the hematopoietic system reconstituting cells will be transplanted. The term "allogeneic" as used herein means that the recipient is not the natural source from which the hematopoietic system reconstituting cells have been removed. Major histocompatability complex antigens (also called human leukocyte antigens, HLA) are protein molecules expressed on the surface of cells that confer a unique antigenic identity to these cells. MHC/HLA antigens are target molecules that are recognized by certain immune effector cells T-cells and Natural Killer (NK) cells! as being derived from the same source of hematopoietic reconstituting stem cells as the immune effector cells ("self") or as being derived from another source of hematopoietic reconstituting cells ("non-self").

Mononuclear cells are cells of the hematopoietic system identified by a round, nonsegmented nucleus. Mononuclear cells can include T cells, NK cells, monocytes, mixtures of T cells, NK cells or monocytes.

Properties of T cells include the expression of a complex of proteins on their cell surfaces that include the CD3 antigen and the T cell receptor (TCR) that can bind to MHC/HLA molecules expressed on the surface of other cells. The presence of the CD3/TCR complex allows T cells to recognize cells from genetically different individuals as expressing "non-self" MHC/HLA antigens and to recognize virally infected cells and tumor cells from the same individual as expressing "altered self" MHC/HLA antigens. T cells are able to bind to and kill cells that express "non-self" and "altered self" MHC/HLA by the activation of specific cytolytic enzymes; they regulate (including stimulation and inhibition) T cell and B cell proliferation and antibody production in response to a specific antigen; they release protein molecules called cytokines that stimulate or inhibit the immune response; and they undergo multiple rounds of cell division and produce daughter cells with similar biologic properties as the parent cell. Examples of T cells with some attributes of NK cells include cells that express both the CD3 (T cell specific) and the CD56 (NK cell specific) antigens.

Properties of NK cells include: the expression of antigens on their cell surface that include one or more of the following: CD16, CD56, and CD57 and the absence of the alpha/beta or gamma/delta TCR complex expressed on the cell surface; the ability to bind to and kill cells that fail to express "self" MHC/HLA antigens by the activation of specific cytolytic enzymes; the ability to kill tumor cells from a genetically unrelated individual; the ability to release protein molecules called cytokines that stimulate or inhibit the immune response; and the ability to undergo multiple rounds of cell division and produce daughter cells with similar biologic properties as the parent cell.

Properties of monocytes include the ability to engulf (phagocytosis) bacteria and "non-self" cells; the elaboration of cytokines that stimulate T cells and NK cells; the release of molecules that cause inflamation; and the presentation of antigens to T cells.

The mononuclear cells are "treated so as to render them incapable of proliferating and causing a lethal GvHD effect." As used herein, this phrase means that the mononuclear cells can be treated, for example by exposure to a source of ionizing radiation, which will have the effect of preventing lethal GvHD. It is believed that the treatment sufficiently hinders the mononuclear cell proliferation such that they do not cause a lethal GvHD in the patient. Sources of ionizing radiation can include but are not limited to gamma radiation produced by the nuclear decay of a radio-isotope (Till and McCulloch, 1961, "A direct measurement of the radiation sensitivity of normal mouse bone marrow cells", Radiation Research, 14:213-222) and a linear accelerator which produces high energy X-rays (Gratwohl et al. (1988), "Irradiated buffy coat following T cell depleted bone marrow transplants", Bone Marrow Transplantation, 3:577-582). Using gamma radiation as the source of the ionizing radiation, the mononuclear cells, in one example, can be irradiated with between 250 and 2000 rads of radiation. An alternative range of irradiation doses is between 500 and 1500 rads of irradiation, with 500 to 1000 rads of irradiation being another range. In another example, the mononuclear cells can also be irradiated with gamma radiation using any range of any values between 250 and 5000 rads, for example, 350 and 1900, 450 and 1800, 550 and 1700, etc. or combinations thereof (e.g., 250 and 1900).

Alternatively, the mononuclear cells can be treated with cytotoxic chemotherapeutic drugs to render the cells incapable of proliferating and causing a lethal GvHD. Cytotoxic chemotherapeutic drugs act by cross-linking DNA or otherwise interfering with normal cellular metabolism so as to render cells incapable of proliferating (Chabner (1993) "Anticancer Drugs" in Cancer: Principles and Practice of Oncology, Fourth Edition, eds. DeVita, Hellman, and Rosenberg. pp. 325-417. J.B. Lippincott publishers, Philadelphia). Examples of such cytotoxic chemotherapeutic drugs that could be employed in the present invention include, but are not limited to, mitomycin C, bleomycin, actinomycin D, fludarabine, doxirubicin, daunorubicin, mitoxanthrone, cytarabine, streptozocin and amsacrine. The mononuclear cells are incubated with a sufficient concentration of the cytotoxic drug so as to result in their eventual death. For example, 5×10⁷ mononuclear cells/ml can be incubated with 50 μg/ml mitomycin C in phosphate buffered saline for 20 minutes at 37°. Mitomycin C enters the mononuclear cells and acts to cross-link DNA. Unbound mitomycin C is then removed by diluting the cell suspension with PBS, centrifuging the mixture at 300×g for 5 minutes and removing the supernatant. Fresh PBS is added to the cell pellet and the washing procedure is repeated two additional times. The cell pellet is then resuspended in PBS or a similar physiologic salt solution.

The mononuclear cells are treated, for example, by either ionizing radiation or cytotoxic chemotherapeutic drugs to render the cells substantially incapable of proliferating but such that the mononuclear cells are effective in enhancing subsequent engraftment of the hematopoietic system reconstituting cells in the recipient, for example, by neutralizing restricting host cells. This enhancement may be due to mononuclear cells conditioning the recipient to successfully accept the transplanted cells without proliferating in the recipient and mounting an immune response against the recipient's cells. The mononuclear cells can also exert a graft versus leukemia effect by which they aid in the elimination of residual cancer cells in the recipient.

The treated mononuclear cells can be administered to the recipient at any time prior to the administration of the hematopoietic system reconstituting cells and preferably are administered up to ten days prior to administration of the hematopoietic system reconstituting cells. Most preferably, the treated mononuclear cells are administered to the recipient between one and five days prior to the administration of the hematopoietic system reconstituting cells. Any range of treatment, e.g., one to nine, two to eight, three to seven, one to two, one to three, zero to one, zero to two days, etc. are also provided.

The hematopoietic system reconstituting cells and the treated mononuclear cells can be from the same donor source or they can be from different donors. These donor source cells include cells which are propogated in vitro or derived in vitro from a less differentiated cell type of the donor source, for example, from a yolk sac or other embryonic fetal tissue source such as embryonic stem cells.

The amount of treated mononuclear cells administered to the recipient, in one example, can be between 0.05×10⁶ and 30×10⁶ cells/kg of the recipient's body weight. Subranges of treated mononuclear cells are also provided, for example 5.0 to 25×10⁶, 10 to 20×10⁶, 5.0 to 20×10⁶, etc.

The hematopoietic system reconstituting cells administered to the recipient can, in one example, be present in a source population of between 0.2×10⁸ and 4.0×10⁸, or ranges there between, donor bone marrow cells/kg of the recipient's body weight. The bone marrow cells can be obtained from the donor by standard bone marrow aspiration techniques known in the art. Bone marrow cells are removed from the donor by placing a hollow needle into the marrow space and withdrawing a quantity of marrow cells by aspiration.

Alternatively, the hematopoietic system reconstituting cells administered to the recipient can, in one example, be present in a source population of between 1.0×10⁸ and 40×10⁸, or ranges there between, donor cytokine mobilized peripheral blood stem cells/kg of recipient's body weight. Peripheral blood cells can be obtained from the donor, for example, by standard phlebotomy or apheresis techniques. Phlebotomy is performed by placing a hollow needle into a vein and withdrawing a quantity of whole blood using aspiration or gravity. Apheresis is performed in a similar manner to phlebotomy except the whole blood is anticoagulated and then separated into the constituent formed cellular elements by centrifugation. The mononuclear cell fraction is retained and the remaining plasma and other cellular elements (red blood cells, granulocytes, platelets) are returned to the donor by intravenous infusion.

Peripheral blood stem cells can be cytokine mobilized by injecting the donor with hematopoietic growth factors such as Granulocyte colony stimulating factor (G-CSF), granulocyte-monocyte colony stimulating factor (GM-CSF), stem cell factor (SCF) subcutaneously or intravenously in amounts sufficient to cause movement of hematopoietic stem cells from the bone marrow space into the peripheral circulation. The hematopoietic reconstituting cells can also be derived from fetal or embryonic human tissue that is processed and/or cultured in vitro so as to increase the numbers or purity of primitave hematopoietic elements.

The hematopoietic system reconstituting cells administered to the recipient can be T cell-depleted to prevent the development of GvHD. The cell population is depleted of T cells by one of many methods known to one skilled in the art (Blazer et al., (1985) "Comparison of three techniques for the ex vivo elimination of T cells from human bone marrow." Experimental Hematology 13:123-128) or by using affinity chromatography, as described below. In addition, the hematopoietic system reconstituting cells administered to the recipient can also be hematopoietic system cells that have been enriched from the source population. The source population can be either donor bone marrow cells or donor peripheral blood cells. The hematopoietic system reconstituting cells can be enriched from the source population by selecting cells that express the CD34 antigen, using combinations of denisty centrifugation, immuno-magnetic bead purification, affinity chromatography, and flourescent activated cell sorting, known to those skilled in the art (Baum, C. M., I. L. Weissman et al., (1992) "Isolation of a candidate human hematopoietic stem-cell population" Proc. Natl. Acad. Sci. U.S.A. 89:2804-8; Lansdorp, P. M., H. J. Sutherland et al., (1990) "Selective expression of CD45 isoforms on functional subpopulations of CD34+ hematopoietic cells from human bone marrow." J Exp. Med. 172:363-6; Sato, N., K. Sawada et al., (1991) "Purification of human marrow progenitor cells and demonstration of the direct action of macrophage colony-stimulating factor on colony-forming unit-macrophage" Blood 78:967-74; Smith, C., C. Gasparetto et al., (1991) "Purification and partial characterization of a human hematopoietic precursor population" Blood 77:2122-8; Udomsakdi, C., C. J. Eaves et al., (1991) "Separation of functionally distinct subpopulations of primitive human hemtopoietic cells using rhodamine-123" Exp. Hematol 19:338-42; Udomsakdi, C., P. M. Lansdorp et al., (1992) "Characterization of primitive hematopoietic cells in normal human peripheral blood" Blood 80:2513-21.

The treated mononuclear cells and hematopoietic system reconstituting cells are typically administered to the recipient in a pharmaceutically acceptable carrier by intravenous infusion. Carriers for these cells can include but are not limited to solutions of phosphate buffered saline (PBS) containing a mixture of salts in physiologic concentrations.

The recipient can be treated with antibodies or antisera intended to deplete residual T cells or NK cells. Examples include the administration of 100 μl of antiasialo antisera to mice by intravenous or intraperitoneal injection one to three days prior to the administration of allogeneic bone marrow cells, a treatment that enhances the engraftment of the mice by antigenically mismatched and genetically unrelated tumor cells (Waller et al. (1991) "Growth of primary T-cell non-Hodgkin's lymphomata in SCID-hu mice: requirement for a human lymphoid microenvironment", Blood 78(10):2650-65). Another example includes the intraveneous administration of anti-thymocyte globulin to human patients one to five days prior to the intraveneous infusion of allogeneic bone marrow cells (Storb et al. (1994) "Cyclophosphamide combined with antithymocyte globulin in preparation for allogeneic marrow transplants in patients with aplastic anemia", Blood 84(3):941-9).

In a more specific embodiment, the present invention provides a method of transplanting bone marrow cells from a donor into an allogeneic recipient comprising administering to the recipient, one to five days prior to administration of the bone marrow cells, between 0.05×10⁶ and 30×10⁶ cells/kg of the recipient's body weight of T cells that have been exposed to between 500 and 1000 rads of gamma irradiation; and administering to the recipient between 1.0×10⁸ and 4.0×10⁸ cells/kg of the recipient's body weight of T cell-depleted bone marrow cells.

EXAMPLES Animals

B 10 R. III (H2Kr) mice, aged eight to ten weeks, were purchased from Charles River/Jackson Laboratories. C57B1/6 (H2Kb Thy 1.2) and BA (H2Kb Thy 1.1) mice were bred and maintained in sterile housing at the Emory University Animal Care Facility. Drinking water was acidified to a pH of 2.5.

Donor Cell Preparations

All manipulations of cells were performed with sterile Hanks Buffered Saline Solution (HBSS) containing 3% heat-inactivated fetal bovine serum (HBSS/FBS). Bone marrow cells were harvested from C57B1/6 (H2Kb Thy 1.2) mice by removing the femora and tibia. The bone marrow space was flushed with medium using a 25 guage needle, followed by repeated pipetting to yield a single-cell suspension. Spleenocytes were harvested from BA (H2Kb Thy 1.1) mice by removing the spleen and placing it in a small petri dish. A single cell suspension was generated by flushing the spleen with medium using a 25 gauge needle followed by repeated pipetting.

T Cell Manipulations

Bone marrow cells at a concentration of 2×10⁷ cells per milliliter were incubated with biotinylated αCD3 antibody (Pharmingen, San Diego, Calif.) at a saturating concentration of antibody on ice for 20 minutes, then washed with ten volumes of HBSS/FBS and collected by centrifugation. The cell pellets were suspended in 100 μl of Streptavidin Microbeads (Miltenyi Biotech GmbH) and 200 μl degassed HBSS. This solution was incubated on ice for 20 minutes, then washed as previously described. The cells were run over a Mini Macs magnetic separation column (Miltenyi Biotech, Gmbh). The first fraction collected was depleted of CD3+cells (T cell depleted fraction). The column was removed from the magnetic source and CD3+cells were eluted by washing the column with 0.5 ml HBSS/FBS.

Irradiation of Spleen Cells

Spleen cell suspensions were irradiated to 1000 rads in a single fraction at a dose rate of 1.462 rads/sec (0.01462 Gy/sec).

Antiasialo Treatment

Recipient mice were injected intraveneously with 100 ul (0.1 ml) of antiasialo antisera.

Irradiation and Reconstitution

Recipient animals B10RJII (H2Kr) were exposed to 10 Gy (1000 rads) of radiation from a Cs¹³⁷ source (Gamacell Irradiator, Canada) at a dose rate of 0.01462 Gy/sec (1.462 rads/sec), with the total dose being delivered in two equal fractions separated by a five hour rest. Bone marrow and spleen cell suspensions were transplanted to irradiated animals by retroorbital injection under methoxyflurane anesthesia. The recipient animals were maintained on oral aqueous antibiotics (Neomycin Sulfate Polymyxin B Sulfate 6000 units/mg, Sigma Chemical, St. Louis) for four weeks after the delivery of the radiation.

Analysis of Transplant Recipients

Beginning at one month after transplant, mice were anesthetized with methoxyflurane and about 200 μl of peripheral blood was collected from the retroorbital sinus into 400 μl of HBSS plus 100 U/ml sodium heparin. A 2 ml volume of 3% Dextran T500 (Pharmacia LKB, Piscataway, N.J.) in HBSS was added to each blood sample and the mixture was incubated for 20 min at room temperature to allow sedimentation of red blood cells (RBC). The upper layer of RBC-depleted fluid was transferred to a new tube. Cells were collected from this layer by centrifugation and resuspended in 2 ml of cold 0.2% NaCl for one minute followed by the addition of 2 ml of cold 1.6% NaCl to restore isotonicity. Cells were collected by centrifugation, then resuspended in HBSS/FBS at a cell concentration of approximately 1×10⁶ cells/100 μl for immunofluorescent staining. Donor and host-derived cells were distinguished with monoclonal antibodies specific for the MHC (H2Kb). Dual-color immunofluorescence, using a fluorescein-conjugated anti-Thy 1.1 reagent and allophycocyanin-conjugated anti-Thy 1.2 reagent was performed to enumerate donor-derived T cells from bone marrow (Thy 1.2) and spleen (Thy 1.1).

Results

Table 1 shows the fraction of mice surviving thirty days after receiving a lethal dose of ionizing radiation followed by intravenous infusion of a small number (500,000 cells; 0.2×10⁸ cells/kg) of mouse marrow cells. The survival was greatest (80%) among mice that received bone marrow cells from genetically identical (syngeneic) litter mates, and lowest (0%) among mice that received bone marrow from genetically dissimilar (allogeneic) donors. The allogeneic donors expressed the "b" antigen on their MHC molecules while the recipients expressed the "r" antigen.

The two strains of mice are completely (filly) mismatched at the MHC antigen loci. An analogous situation in humans would be donors and patients mismatched at all six of the HLA antigen loci. It is worth noting that mortality is 60% due to graft failure and/or GvHD for genetically related human donors and patients mismatched at two out of six HLA antigens.

The survival of mice that received allogeneic bone marrow cells was increased to 80% by the co-administration of unirradiated allogeneic spleen cells; however these recipient mice were at risk for developing GvHD as assessed by the survival of large numbers (+++) of mature T cells in their peripheral blood derived from the infused spleenocytes. Mice that received allogeneic bone marrow cells in combination with irradiated spleen cells had a survival that was intermediate between the group that received syngeneic bone marrow and the group that received allogeneic bone marrow cells alone. Recipients of irradiated spleen cells did not have any detectable spleen-derived T cells in their peripheral blood, and are at much lower risk for GvHD. The addition of a single dose of irradiated spleen cells co-administered with the allogeneic bone marrow cells increased survival of recipient mice to 20%; the administration of two doses of irradiated spleen cells, (the first one day prior to the administration of allogeneic bone marrow cells and an additional dose co-administered with the allogeneic bone marrow cells) increased survival to 41%. The injection of anti-asialo antisera preceding the administration of two doses of irradiated spleen cells and the allogeneic bone marrow increased survival to 60%. The function of anti-asialo antisera is to cause in vivo depletion of host NK cells, further reducing the resistance of the irradiated recipient to engraftment by fully allogeneic hematopoietic reconstituting cells.

Administration of Treated Mononuclear Cells and Hematopoietic System Reconstituting Cells to a Human Subject

A patient, diagnosed with a disorder for which transplantation of hemapoietic system reconstituting cells is indicated, can be given about 5×10⁶ treated mononuclear cells/kg isolated from the peripheral blood of the donor by apheresis about two days prior to the administration of the hematopoietic system reconstituting cells. After administration of the treated mononuclear cells, the patient can be given hematopoietic system reconstituting cells either in a source population of about 5×10⁶ CD34+cells/kg isolated by apheresis from the donor's peripheral blood following treatment with GCSF or an equivalent cytokine, or about 2×10⁶ CD34+cells/kg present in donor bone marow obtained by harvesting bone marrow cells. The hematopoietic system reconstituting cells administered to the patient can be T cell-depleted or CD34+cell-enriched from the source population.

Throughout this application, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this invention pertains.

Although the present invention has been described with reference to specific details of certain embodiments thereof, it is not intended that such details should be regarded as limitations upon the scope of the invention except as and to the extent that they are included in the accompanying claims.

                                      TABLE 1                                      __________________________________________________________________________     30 day survival for mice that received a lethal dose of radiation              followed by transplantation with 0.5 × 10.sup.6                          bone marrow cells                                                              __________________________________________________________________________     Day -2                                    anti asialo                                                                    anti-sera                            Day 0  Syngeneic                                                                             Allogeneic                                                                            Allogeneic                                                                            Allogeneic                                                                            5 × 10.sup.6                                                                    5 × 10.sup.6                          Bone marrow                                                                           Bone marrow                                                                           Bone marrow +                                                                         Bone marrow +                                                                         irradiated                                                                            irradiated allo                                           5 × 10.sup.6                                                                    5 × 10.sup.6                                                                    allo spleen                                                                           spleen                                                    allo spleen                                                                           irradiated                                                                     allo spleen                                        Day 1                              Allogeneic                                                                            Allogeneic                                                              Bone marrow +                                                                         Bone marrow +                                                           5 × 10.sup.6                                                                    5 × 10.sup.6                                                      irradiated                                                                            irradiated                                                              allo spleen                                                                           allo spleen                          Day 30 80%    0%     80%    20%    41%    60%                                  Survival (%)                                                                   Number per                                                                            n = 15 n = 24 n = 10 n = 5  n = 17 n = 20                               group                                                                          Donor-derived                                                                         N/A    N/A    100%   100%   100%   100%                                 Hematopoietic                                                                  Reconstruction                                                                 Presence of                                                                           N/A    N/A    +++    -      -      -                                    T-cells from                                                                   allo spleen                                                                    __________________________________________________________________________ 

What is claimed is:
 1. A method of transplanting hematopoietic system reconstituting cells from a donor source into an allogeneic recipient comprising:a) administering to the recipient, prior to or on the same day of the administration of the hematopoietic system reconstituting cells, an amount of mononuclear cells which are treated so as to render them incapable of proliferating and causing a lethal graft versus host disease effect, but which are effective in enhancing subsequent engraftment of the hematopoietic system reconstituting cells in the recipient; and b) administering to the recipient an effective amount of hematopoietic system reconstituting cells.
 2. The method of claim 1, wherein the mononuclear cells are T cells.
 3. The method of claim 1, wherein the mononuclear cells are natural killer cells.
 4. The method of claim 1, wherein the mononuclear cells are a mixture of T cells and natural killer cells.
 5. The method of claim 1, further comprising depleting the recipient's T cells and natural killer cells prior to administration of the hematopoietic system reconstituting cells.
 6. The method of claim 1, wherein the mononuclear cells are treated by exposure to a source of ionizing radiation.
 7. The method of claim 6, wherein the source of ionizing radiation is gamma radiation produced by the nuclear decay of a radio-isotope.
 8. The method of claim 6, wherein the source of ionizing radiation is a linear accelerator which produces high energy X-rays.
 9. The method of claim 6, wherein the amount of irradiation is between 250 and 2000 rads.
 10. The method of claim 6, wherein the amount of irradiation is between 500 and 1500 rads.
 11. The method of claim 6, wherein the amount of irradiation is between 500 and 1000 rads.
 12. The method of claim 1, wherein the treated mononuclear cells are administered to the recipient up to ten days prior to administration of the hematopoietic system reconstituting cells.
 13. The method of claim 1, wherein the treated mononuclear cells are administered to the recipient between one and five days prior to the administration of the hematopoietic system reconstituting cells.
 14. The method of claim 1, wherein the hematopoietic system reconstituting cells and the treated mononuclear cells are from the same donor source.
 15. The method of claim 1, wherein the amount of treated mononuclear cells administered to the recipient is between 0.05×10⁶ and 30×10⁶ cells/kg of the recipient's body weight.
 16. The method of claim 1, wherein the hematopoietic system reconstituting cells administered to the recipient are present in a source population of between 0.2×10⁸ and 4.0×10⁸ donor bone marrow cells/kg of recipient's body weight.
 17. The method of claim 1, wherein the hematopoietic system reconstituting cells administered to the recipient are present in a source population of between 1.0×10⁸ and 40×10⁸ donor cytokine mobilized peripheral blood stem cells/kg of recipient's body weight.
 18. The method of claim 1, wherein the hematopoietic system reconstituting cells that are administered to the recipient are T cell-depleted.
 19. The method of claim 1, wherein the hematopoietic system reconstituting cells that are administered to the recipient are hematopoietic stem cells enriched from the source population.
 20. A method of transplanting bone marrow cells into an allogeneic recipient comprising:a) administering to the recipient, one to five days prior to administration of the bone marrow cells, between 0.05×10⁶ and 30×10⁶ cells/kg of body weight of T cells that have been exposed to between 500 and 1000 rads of irradiation; and b) administering to the recipient between 1.0×10⁸ and 4.0×10⁸ T cell-depleted bone marrow cells/kilogram recipient's body weight. 